The goal of this research program is to interface semiconductor circuitry with nanoparticle-based DNA detection schemes using the technique of Dip Pen Nanolithography (DPN). The project will develop optimize the chemistry needed to immobilize oligonucleotides on semiconductor surfaces in a manner compatible with the DPN process. Modifications of the atomic force microscope/DPN tip to enhance the efficiency of oligonucleotide ink deposition will be pursued and the DPN fabricated substrates will be used to assemble and characterize patterns of DNA functionalized nanoparticles. The project will develop and study new single-label detection schemes based on the electrical and near-field-optical properties of nanoparticles with surface-bound DNA, and will develop proof-of-principle demonstrations of integrated nanoscale biosensor circuitry. Not only do these schemes offer the promise of enhanced sensitivity and selectivity as compared to fluorophore-based detection methods, but their development also addresses fundamental issues of nanoscience in biological systems including those of diffusion, charge transport and energy transfer.